Add geneset score alt. type key to central list
Add geneset score alt. type key to central list

As the strings used in profile metadata directly affect compatibility
with the backend and data loading pipeline, it makes sense to keep them
in a centralised place rather than hard-code them scattered around the
codebase.


Former-commit-id: e16a4677c75d8355cb03445d9617694fde1ecc87
cBioPortal/cbioportal-frontend,cBioPortal/cbioportal-frontend,cBioPortal/cbioportal-frontend,cBioPortal/cbioportal-frontend,alisman/cbioportal-frontend,alisman/cbioportal-frontend,alisman/cbioportal-frontend,cBioPortal/cbioportal-frontend,cBioPortal/cbioportal-frontend,alisman/cbioportal-frontend,alisman/cbioportal-frontend,alisman/cbioportal-frontend